Electromagnetic Fields Objective Questions – Set 1

The force between two long parallel conductors is inversely proportional to

product of current in two conductors.

current in one conductor.

distance between the conductors.

radius of conductors.

Correct!

Wrong!

-

The field at any point on the axis of a current carrying coil will be

zero.

perpendicular to the axis.

at angle of 45° with the axis.

parallel to axis.

Correct!

Wrong!

-

Two parallel plates are separated by a distance D charged by V volt. The field intensity E is given by,

V² / D

V × D

V / D

V × D²

Correct!

Wrong!

-

Two straight parallel conductors carry equal currents in opposite direction. The force between them is

attractive

none of above.

zero

repulsive

Correct!

Wrong!

-

It was suggested by _____________ that the electric field should be imagined to be divided into tubes of force containing a fixed number of line of force

Kelvin

all of above.

Newton

Faraday

Correct!

Wrong!

-

According to Coulomb’s law, the force of attraction or repulsion, between to electrical charges is

directly proportional to the square of the distance between them.

inversely proportional to the square of the distance between them.

directly proportional to the distance between them.

inversely proportional to the distance between them.

Correct!

Wrong!

-

Biot-Savarts law states the relation between magnetic intensity and

All are correct

filament current only.

surface current only.

volume current only.

Correct!

Wrong!

-

Electric flux in coulombs emanating from any surface of a cube containing C coulombs of charge at its centre

Q / 6.

Q / 6ε.

4πQ / 6ε.

Q / 4π.

Correct!

Wrong!

-

The energy stored in the magnetic field at a solenoid 30 cm long & 3 cm diameter wound with 1000 turns of wire carrying a current at 10 amp, is

0.015 joule.

1.15 joule.

0.015 joule.

0.15 joule.

Correct!

Wrong!

-

Whenever the magnetic flux changes with respect to an electric conductor or a coil, an EMF is induced in the conductor is Faraday’s

fourth law

third law

first law

second law

Correct!

Wrong!

-

As a result of reflection from a plane conducting wall, electromagnetic waves acquire an apparent velocity greater than the velocity of light in space. This is called the

normal velocity.

group velocity.

phase velocity.

velocity of propagation.

Correct!

Wrong!

-

The drawback of Daltons atomic structure is that, it says

the atoms can neither be created nor be destroyed.

unique nature of atom.

most of the volume of an atom is empty space.

none of these.

Correct!

Wrong!

-

Inside a hollow conducting sphere

electric field changes with magnitude of the charge.

electric field is zero.

electric field is non zero constant.

electric field changes with distance from the center.

Correct!

Wrong!

-

Electric field intensity (E) at any point in an electric field is equal to

(potential gradient)2.

potential gradient.

(potential gradient)1/2.

(potential gradient)1/3.

Correct!

Wrong!

-

Two infinite parallel metal plates are charged with equal surface charge density of the same polarity. The electric field in the gap between the plates is

dependent on coordinates of field points.

double the field produced by one plate.

zero

same as that produced by one plate.

Correct!

Wrong!

-

Midway between two equal and similar charges, a third equal and similar charge is placed, then this third charged will

remain in stable equilibrium.

will move out of the field of influence of two charges.

not be equilibrium.

be in unstable equilibrium.

Correct!

Wrong!

-

A conductor of length L has carrying current I passing through it, when it is placed parallel to strong magnetic field. The force experienced by the conductor will be

BI2L.

BIL.

BL2I.

zero

Correct!

Wrong!

-

Inside a hollow conducting sphere

electric field is a non zero constant.

electric field changes with distance from the center of the sphere.

electric field changes with magnitude of the charge given to the conductor.

electric field is zero.

Correct!

Wrong!

-

The change of cross sectional area of conductor in magnetic field will affect

reluctance and resistance of conductor both in the same way.

resistance of conductor.

none of above.

reluctance of conductor.

Correct!

Wrong!

-

The right hand rule for determining the direction of the induced EMF was introduced by

Maxwell

Lenz

Fleming

Faraday

Correct!

Wrong!

-

A point pole has a strength of 4π × 10-7 weber. The force in newtons on a point pole of 4π × 1.5 × 10-4 weber placed at a distance of 10 cm from it will be

3.75 N.

15 N.

7.5 N.

20 N.

Correct!

Wrong!

-

Cork Screw rule is used to find

direction of magnetic field.

direction of emf.

direction of electric field.

direction of current.

Correct!

Wrong!

-

Conductor is constant and field is varying then emf will induce. This principle is called

virtually induced emf.

static induced emf.

dynamically induced emf.

none of these

Correct!

Wrong!

-

A long wire composed of a smooth round conductor runs above and parallel to the ground (assumed to be a large conducting plane). A high voltage exists between the conductor and the ground. The maximum electric stress occurs at

lower surface of the conductor.

midway between the conductor and ground.

upper surface of the conductor.

the ground surface.

Correct!

Wrong!

-

Which of the following represents ohms law

J = σE

I = GV

All of the above

V = RI

Correct!

Wrong!

-

Ohm’s law in point from field theory can be expressed as

J = σE.

V = IR.

R = ρ × ( l / A).

J = E / σ.

Correct!

Wrong!

-

Two long parallel conductors carry 100 A. If the conductors are separated by 20 mm, the force per meter of length of each conductor will be

100 N.

0.01 N.

1 N.

0.1 N.

Correct!

Wrong!

-

A metal surface with 1 meter radius and surface charge density of 20 coulombs / m2 is enclosed in a 10 m side. The total outward electric displacement normal to the surface of the cube is

80π coulombs.

none of these.

40π coulombs.

10π coulombs.

Correct!

Wrong!

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A wire carrying current is bent in the form of a circular loop. Then the magnetic field around each portion of the wire will be